Anybody tried to not run any active filtration but continuously change water instead?

[spacey]

So... I was thinking the other day, all the gear we buy and supplements we dose, other than return pump, powerheads, lights and heater, is there just to strip the water off the dirt of various types continuously generated by life in our tanks. And yet, water changes are still very highly recommended at ~10% or so rate per week.

What if, we just stopped doing anything to the water, except keep changing it but at a higher rate to compensate. Say 25 or 50% per week. The powerheads do in effect bio filtration by pushing water through LR, but we need those for flow for the corals anyway so not including those in the questionable gear category.

The cost profile is different. You'd be paying more for salt, but less to none for supplements, carbon, GFO, biopellets etc. Not to mention all the devices like reactors, skimmers dosers etc. All you would need would be:

1. Lights
2. Powerheads / flow
3. Return pump
4. Heater (and/or chiller if need be).
5. ATO
6. Auto W/C setup

I just did some rough math in my head for my system, 50 Gal display + 20 Gal sump, hopefully to be expanded soon by additional 100 Gal display. If I use Reef Crystals, I can get a box good for 200 Gal (though I have to double check if it really is 200 at 35 ppt), this runs me anywhere between $55 to $75 / per box. W/a $170 Gal system, if I did a 100% w/c per month, that would be $55-$75 / month. But then I don't have to pay for anything else, I can shrink the sump to literally just a floss pad or a sock, heater and a return pump. With a spot for probes, ATO and that's it. The sump could be small regardless of the size of the system.

I've read some people run w/out any water changes too, but I find that highly suspect and/or magical in what they must be doing to their systems, so that is I think the exact opposite of what I am saying here - monster water changes, and no chemical filtration or dosing. This would include any macro algae reactors, which isn't chemical strictly speaking.

 

[Casket_Case]

That’s what they do in a reef jar or bowl no filtration just water changes

 

[WV Reefer]

So... I was thinking the other day, all the gear we buy and supplements we dose, other than return pump, powerheads, lights and heater, is there just to strip the water off the dirt of various types continuously generated by life in our tanks. And yet, water changes are still very highly recommended at ~10% or so rate per week.

What if, we just stopped doing anything to the water, except keep changing it but at a higher rate to compensate. Say 25 or 50% per week. The powerheads do in effect bio filtration by pushing water through LR, but we need those for flow for the corals anyway so not including those in the questionable gear category.

The cost profile is different. You'd be paying more for salt, but less to none for supplements, carbon, GFO, biopellets etc. Not to mention all the devices like reactors, skimmers dosers etc. All you would need would be:

1. Lights
2. Powerheads / flow
3. Return pump
4. Heater (and/or chiller if need be).
5. ATO
6. Auto W/C setup

I just did some rough math in my head for my system, 50 Gal display + 20 Gal sump, hopefully to be expanded soon by additional 100 Gal display. If I use Reef Crystals, I can get a box good for 200 Gal (though I have to double check if it really is 200 at 35 ppt), this runs me anywhere between $55 to $75 / per box. W/a $170 Gal system, if I did a 100% w/c per month, that would be $55-$75 / month. But then I don't have to pay for anything else, I can shrink the sump to literally just a floss pad or a sock, heater and a return pump. With a spot for probes, ATO and that's it. The sump could be small regardless of the size of the system.

I've read some people run w/out any water changes too, but I find that highly suspect and/or magical in what they must be doing to their systems, so that is I think the exact opposite of what I am saying here - monster water changes, and no chemical filtration or dosing. This would include any macro algae reactors, which isn't chemical strictly speaking.

I run all my reefs with just lights, powerheads and heat.

 

[flampton]

I'm not sure what you mean by chemical filtration? The GFO? Most reefs run on mostly mechanical filtration methods. These methods include floss or socks, carbon dosing (macroalgae or purposefully added) what have you they're all finished mechanically. You harvest macro, you skim, you chnage socks. And GFO is definitely not a requirement.

Your costs over time will be outrageous compared to someone who uses various mechanical filtration means.
So lets say you buy a $500 skimmer and choose carbon dosing. So you must add vinegar. Lets say you get up to a 100ml a day. Which is a lot!! So a gallon of vinegar is like 3 bucks at most. So that's more than a months worth.

Okay now using your above amounts of $55 a month, even though you'll only get like 140 gallons out it. The carbon dosing and high priced skimmer are now equal within a year. And that's using that low ball number. And then time investment. I'm not sure if you're in a situation were time is money, but if you are you best have a complete setup that minimizes the water change experience. Then add up the costs for this salt water mixing station. You'll be far into the negatives compared to someone carbon dosing, using a skimmer, and maybe a trace element to boot and possibly doing a water change a few times a year at best.

And your massive fresh saltwater changes will be stressing your occupants way more than small water changes. And your removing a decent sized sump which allows the water volume to be greater and thus more stable.

It's a doable but definitely more expensive path in the long run...

 

[jda]

Some of the things that you are leaving out have purposes other than to just filter the water. The removal of heavy metals and gas exchange from a protein skimmer is more important than removing DOCs, IMO.

I have not thought about this much, but it seems, on the surface, that there are likely some unintended consequences to what you are suggesting.

Chemical filtration is not necessary, IMO. It is used to cover some bio filtration or other method that is not working correctly, or is not appropriately sized. You can avoid it, but sometimes it works better than other methods especially if you are cramped for space (GFO when no room for a fuge, for example). I would not consider any chemicals a necessity.

A lot of us would need to dose regardless. The alk in my 300g system can fall from 7.X to 4.0 in about 12-18 hours without a doser, or CaRx in my case, and water changes could never keep up.

IMO, there is no way that I can do without a doser/CaRx, skimmer and I don't use chemicals... so not sure where the benefit is for people like me.

 

[Spare time]

I would never do that as it is very inefficient with costs and water changes can be stressful for the inhabitants. I don't use any filter media but carbon because my fuge and socks handle everything so my tank cost per a month is very low.

 

[LadyTang2]

I believe in a medium-high demand tank ca and alk would be depleted at a rate greater than a WC could replenish (unless the WC rate was so high it would def be cost ineffective). You'd be looking at 100% once a week depending. Skimmer good for aeration. Continuous WCs are great but alone dont really work.

 

[Kershaw]

This is interesting, I wonder about the stability especially if you end up with a batch of salt that is dramatically different then the last.
the idea of running a tank with out skimmer scares me, even though there are people who do it successfully

 

[Spare time]

This is interesting, I wonder about the stability especially if you end up with a batch of salt that is dramatically different then the last.
the idea of running a tank with out skimmer scares me, even though there are people who do it successfully

I don't .

 

[spacey]

Ok, so one modification, which I was thinking but not clearly stated, or stated at all. The w/c setup would be continuous, or as close as possible. This would remove the stress of large w/c as well as dosing to a significant or even complete degree, assuming the salt has Alk, Ca and Mg at levels you like. Some systems would still need possibly more but it would be reduced.

One thing I can't tell, and naturally that would be variable, is how much w/c would compensate for 100% of dosing. So this would be a range.

If achievable, this system would simplify the technical complexity and cut the amount of gear, maybe? I consider mixing stations to not be very complex for small to moderate size systems. It's essentially a multiple of brute containers with a simple power head or two. Maybe a heater if change rate is high enough.

And since the water is exchanged with brand new continuously, presumably all sorts of issues would go away as well.

 

[spacey]

This is interesting, I wonder about the stability especially if you end up with a batch of salt that is dramatically different then the last.
the idea of running a tank with out skimmer scares me, even though there are people who do it successfully

Good point about the bad salt... This would have to be checked/controlled when preparing.

Not running a Skimmer is not a problem of you keep taking out old water. Skimmer is not going to be as good as water removal and replacement w/new water.

 

[xiaoxiy]

I do automatic water changes (~3% daily) but also run carbon as a back up. My water gets yellower without carbon, even with almost 20% water change weekly.

 

[YankeeTankee]

If you were to try this, I'd suggest a single pump motor with two heads. Separate dosing motors with heads will have some variation in dosing vol that would build over time and effect your salinity/ATO. Keep in mind even with this, tubing blockages (one side flowing freely, other side partially or fully occluded) can still cause big issues.

It is likely you would still need to dose Ca/Alk unless you have a very low coral load. You will have little control on tweaking levels of any kind and the rates of depletion/addition will be out of whack which is why you don't see folks doing what you're suggesting. Rather than choose an arbitrary %/month value, if you changed the water at a rate that lead to some important parameter being in a range you want, that would seem better. Good news is with this approach is if you discover you need more equipment you just can add it as you are starting with very little, less chance for equipment purchase regrets!

 

[jda]

If you are experiencing problems when changing water, then you are not doing something right. Some of my corals are exposed to the air for 15-20 minutes and do not slime, retract polyps or are otherwise stressed during the change. Just pay close attention to the parameters, heat and make sure that the water is really aerated so that the same balance of co2, o2, pH, etc. is the same.

There are good salts that do not vary from batch to batch - this is why IO is still the go-to for many reefers. I have never had issues with Tropic Marin being variable either.

 

[flampton]

I'm not sure why you think auto water change will always beat a skimmer.
For instance...
Small water changes are much less effective at removing contaminants then large water changes. And the difference can be dramatic.
Lets say for instance I have a contaminant that is at 100 ppb
And I perform a 90% water change. That will bring it down to 10 ppb instantly
Lets say instead I do 30-3% changes. Well you'll be at 41.3 ppb (if it doesn't increase back up over those 30 days)

So yeah auto water changes are good for replenishment but poor for removing contaminants.
A skimmer running 24 hours and the contaminant is susceptible to skimming and you'll be much better off.
And if not it the compound might adsorb to carbon and again you'll be much better off than small water changes.
Or it sticks to a sock, or whatever but...

AWC is a replenishment system and not really a decon system. I'd rather dose trace minerals and use some mechanical filtration rather than go through that hassle and expense.

 

[ichthyogeek]

^^Basically what Flampton is saying. As much as I'd love for our tanks to use linear equations, we get stuck with really crazy recurrence equations (and yes, I did have to ask one of my college buddies to remind me what "an equation where the present value is dependent on the past value" was to get that term).

Take the following equation that one can apply for nitrate:
Y = % water changed every week
X = amount of nitrates added to the tank every week (fish waste, etc.)
f(z) = amount of nitrates remaining in the tank every week.

f(z) = (1-Y) * (f(z-1)+X)
For example, you change 10% of water (Y) every week, when fish are adding in 10 ppm nitrate (X) every week:
f(z)=(1-.1)*(f(z-1)+10))
f(0) = 0

You can run a similar equation with something like calcium as well.
G = calcium goal (in our case, typically 450 ppm)
Y = % water changed every week
X = amount of calcium taken up every week
f(z) = amount of calcium remaining in the tank every week

f(z) = Y*G + (1-Y)*(f(z-1)-X)
Example: you change 10% of water (Y) every week, when corals take up 50 ppm calcium(X) each week.
f(0) = 450
f(z) = 10%(450) + (1-Y)(f(z-1) - 50)

If you have something like WolframAlphaPro, you could easily graph things out...but you can also do something similar with an Excel, Google Sheet, or Numbers sheet.
Nitrate example:

	f(0)	Nitrates/week	%water changed
	0	10	.1
Values:	f(1) = (f(0)+Nitrates/Week)* %water changed	f(2) = (f(1)+Nitrates/Week)* %water changed	etc. ad nauseum.

and you can do the same with Calcium etc.

 

[syrinx]

Its easy to balance a tank to exist and thrive with no filters or additives-one of my display tanks is just that. What is difficult is to balance ones hopes, dreams, and expectations-as they seldom fit the equation for success.

 

[xxkenny90xx]

I have 3 tanks. 2 are fowlrs and use nothing but live rock for filtration. Lots of LIVE rock. The 3rd is my reef and it has a skimmer and chaeto. And kalk in the ato. I think what your looking at doing really works best for fowlrs.

 

[Josh@BVA]

Yes I think when u rely on heavy bio mass for filtration things run Naturally and can be more resistant to change. I do water changes every few weeks and only run socks during water change. Lots of marine pure spheres and liverock. I have about 8 fish and a dozen coral species